


To Thine Own Self Be True

by This_is_your_Heichou_speaking



Category: Harry Potter - J. K. Rowling
Genre: Alpha Harrison Black, Alpha/Beta/Omega Dynamics, Bottom Harry Potter, Daddy Kink, Intersex Harry Potter, M/M, Omega Harry Potter, Oral Sex, Selfcest, Teacher-Student Relationship, Top Harrison Black, Vaginal Fingering, Vaginal Sex, mention of breeding kink
Language: English
Status: Completed
Published: 2019-12-31
Updated: 2019-12-31
Packaged: 2021-02-27 08:55:19
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 7,902
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22054411
Author URL: https://archiveofourown.org/users/This_is_your_Heichou_speaking/pseuds/This_is_your_Heichou_speaking
Summary: Harry finds himself out of time, in a world not quite his own.
Relationships: Harry Potter/Harry Potter
Comments: 40
Kudos: 1034





	To Thine Own Self Be True

**Author's Note:**

  * For [Zombu7](https://archiveofourown.org/users/Zombu7/gifts).



> Inspired by Zombu, who is by far the thirstiest person I know for Harrycest and also is the person that talked me into this.
> 
> Also thanks to [Miraculous](https://archiveofourown.org/users/Miraculous/pseuds/Miraculous) for betaing ❤️

It was odd, sitting once again in a Hogwarts that he hadn't seen for so many years. On one hand it felt nostalgic—the great hall glittered with the same awe and magic as it had when he'd first stepped foot in it at age eleven. And a part of him felt like he could slip into the memories, pretend he was just another student, excited to start the new year again. But there were too many differences that were too obvious, and made it impossible to fall fully into the fantasy. For one, instead of sitting amongst the other children on the Gryffindor table, he sat with the Professors as one of them.

And, more surprisingly, there was already a Harry Potter sitting on the Gryffindor table, and it wasn't him.

He looked just like Harrison had when he'd been sixteen, and yet… not. He seemed softer than Harrison had ever felt, his hair a mess of curls falling down to the small of his back. He was speaking animatedly to a Ron and Hermione who seemed achingly familiar, so much so that Harrison couldn't help the pang of sorrow in his chest. But they too were different, untouched by the war in the way his own friends had been, and so the feeling passed quickly.

And still, he couldn't stop staring at himself—at Harry. The boy was short and round-faced, gentle in a way Harrison hadn't ever gotten the chance to be. He found himself cataloguing these differences, the ones that made them look so disparate, and felt an odd ache in his chest. That was Harry Potter, omega son of James and Lily Potter. It wasn't him. He'd never be Harry Potter again, and he'd have to reconcile himself to that sooner or later.

As he watched, Harry looked up at him, almost as if sensing his gaze. His eyes were clear and happy, unclouded with pain or sorrow or stress. He smiled up at Harrison, twirling a lock of hair around his index finger. Harrison found he couldn't look away from the sight, and he knew he was staring for what was surely an inappropriate length of time. Harry flushed a pretty, soft pink in response to his gaze, and suddenly Harrison's mind stopped working altogether.

But no. Even if it was another Harry, it was still _him_. He couldn't possibly be thinking of— couldn't possibly want to—

It didn't bear thinking about. He turned away and back to his meal, ignoring the gaze on him like he'd ignored his own emotions and wants and needs for so long. This was nothing different. Harrison would weather through this too.

* * *

"I want him."

The words had escaped Harry's lips before he even realised he'd thought them. Ron and Hermione fell silent, and then—

"He looks a lot like you, mate."

Harry finally turned away from the sight of their new professor. The man was ignoring him now, but Harry had seen the glimmer of interest in his eyes, and he knew lust when he saw it.

"What are you talking about?" He replied. "He's obviously an Alpha, he practically _exudes_ dominance. And look at his hair! It's a mess!"

"So was yours before you grew it out," Hermione piped in. She smirked when Harry glared at her. "I didn't realise you were so narcissistic, Harry," she teased.

"I'm not! I just…" And he turned back to Harrison Black. The man was moving his peas around on his plate, clearly not very hungry, and Harry unconsciously began to imitate him. His eyes kept dropping to what he could see of the professor's legs beneath the table, and the space between them. It was far too shadowed to really make anything out, but Professor Black wore no robe, and Harry couldn't help but wonder about—

"I bet he has a _huge_ cock," he sighed. Ron choked, and Harry flushed when he realised he'd said that part aloud.

"Harry!" He whined. Harry smiled sheepishly, tucking his hair behind his ear, and apologised. But Ron was used to Harry's vulgar comments, had heard in more detail than he'd ever wanted what Harry got up to with the other boys, so he waved it off.

There was an awkward silence. Hermione nibbled on her toast and watched Harry with knowing eyes, and Harry only lasted three minutes before he couldn't hold it in any longer.

"It's just, I can _smell_ him from here," he moaned. "I need that cock in me by the end of this week or I'll _die_. Do you want to see me dead, Hermione? Do you?"

"Of course not, Harry," she replied, calm as you please. She tapped the table thoughtfully. "I'm just saying, you don't know anything about him. He might not be into men, or not be into omegas. Or maybe he already _has_ a partner. You never know."

Harry shook his head, once again looking up at the Head Table. Professor Black had tried to sip his coffee just as Hagrid had gotten up, and was now frantically trying to wipe at the spill on his shirt as Dumbledore advised him to dab. Harry wanted to be up there himself, feeling up Professor Black's no doubt beautifully sculpted chest as he _dabbed_ away. As it was, he just watched him, thinking to himself that the professor seemed far more endearing than he'd first appeared.

"I don't know, Hermione," he murmured. "I know I don't really know anything about him, but he seems very… _earnest_."

Perhaps there was a lover under that hardened shell after all. Harry was determined to see it revealed.

* * *

Over the next few days, Harry tried _everything_. At first he just paid Professor Black rapt attention, smiling and fluttering his eyelashes at the man in the way he knew got all the boys. When that didn't work, he did everything from making barely-concealed innuendos to bending over in front of Professor Black's face. By the end of the week he'd resorted to flashing his neck at Professor Black every time they were even remotely alone. He enjoyed the thrill it gave him, watching Professor Black's eyes go dark and hungry.

But even so, nothing really worked. Harry couldn't help but grow frustrated, because he could _see_ the interest in his professor's face, could see the badly-hidden lust in the way he went stiff and awkward whenever Harry smiled suggestively at him. But Professor Black never reacted. He never responded favourably to any of Harry's attempts, instead choosing to turn away.

So it continued until Thursday afternoon that same week, period four, when Professor Black decided to call Hermione up to the front of the class for a mock duel.

"Miss Granger's a good volunteer for this, she knows quite a range of spells." Professor Black said in his deep, soothing voice. Harry sighed, admittedly already a little lovesick, and lazily propped up his chin in his hand to watch. Professor Black shook off his outer robe and swiftly folded up his sleeves, and Harry bit his lip when the man's forearms were revealed. They were so firm and thick, beautifully muscled, and there was a pink scar that ran up from the side of his left wrist, and disappeared under the sleeve. Harry watched the professor's muscles flex, and—despite himself, felt his sex growing wet.

He flushed, and pushed his legs together. Admittedly he had already been pretty open about how attracted he was to Professor Black, but to be so easily aroused by just a flash of forearm? Harry couldn't help but worry that he might be in deeper than he'd realised.

Professor Black got into a dueling stance, and Hermione mirrored him, her eyes focused. He smiled kindly at her, and then the professor was sending an _Expelliarmus_ at Hermione, and she could only focus on countering. What followed was Professor Black sending spell after spell at Hermione, and Hermione barely countering in time. At some point, Professor Black sent up a cloud of dust he'd conjured and blinded her, and as he did, turned to the class.

"This is what I mean by _a range of spells_ ," he told them. "Use your environment, and your knowledge from other classes to overcome your opponent. A lot of beginners make the mistake of sticking to just defensive spells and curses, but that just makes them predictable."

The class ' _aaah_ 'ed and nodded. Harry was in awe. The professor was moving almost too fast for Hermione to counter, but it was obvious that he was going easy on her. He was clearly a skilled dueler, and the casual show of strength and ability got to Harry more than he'd like to admit.

Of course, Harry had known what he preferred already—he tended often towards the muscled beaters; the older Gryffindor boys who spent their mornings working out; the larger, broader boys—but what were school boys compared to Professor Black? They all seemed to pale in comparison to his casual, easy confidence, and Harry felt helplessly entranced.

And then Hermione, quick learner that she was, splashed Professor Black with an _Aguamenti_ to distract him, and Harry was treated to the unbearably delicious sight of the man in soaking wet clothes. His white collared shirt had gone almost transparent, sticking to his every muscle and highlighting the cut of his chest, and even his dark, thick trousers seemed to plaster themselves to the shape of Professor Black's coc—

Harry whimpered, and banged his head on the table. He was so wet, he wondered if he'd soaked through his own trousers. But Harry couldn't even really worry about that, because he had never wanted anybody more that he wanted Professor Black's cock inside him right now.

And so Harry, deliberately, leaned his chair back and eyed the professor in a way that wasn't subtle at all. "Why, professor, if you wanted to show off so bad you could have just stripped it all off," he said. Professor Black's eyes went to his, his expression so calm and impassive that it cut of any snickers before they even started.

He smiled tightly, like he knew he was setting up a trap for himself, but didn't know how to get out of it. "Detention this evening, Mr Potter."

Harry had to suppress his own smug smile.

* * *

That evening, Harry found himself at Professor Black's office ten minutes before his detention was due to start. He knew he'd seem eager—almost too eager, and with anyone else he'd have been sure to cultivate a careful air of aloofness, just to make sure his temporary partners remained temporary and casual. But Professor Black was different. Harry could tell be needed to be a little more forceful with him—it was obvious the man was in denial about many things, and he didn't seem the type to change his mind based on soft words alone.

And, admittedly, Harry found himself overly fascinated with the man. He was the most attractive alpha Harry had ever met—and not just physically.

And more than that, Harry couldn't forget what Ron had said, even if it had only been a joke in passing. Professor Black really _did_ look like him. He was older, of course, and much taller and broader than Harry was, but the shape and colour of his eyes, his mouth, the way he bit the ends of his quills and tapped his finger against the table when impatient—it was all so similar that Harry had to wonder. 

He knocked on the door, and waited.

The door swung open almost as soon as he touched it. Harry wasted no time in entering, and was greeted with the sight of Professor Black bent over his desk, frowning at the stack of papers before him.

He had his sleeves folded up to his elbows again, and his robe hung across the back of his desk. Harry felt a little faint, his eyes focused on the edge of black that he could see from beneath the sleeve now—was that a tattoo? He almost tripped, not watching where he was going, and made an aborted sound that was something between a whimper and a yelp.

Professor Black looked up. He stared at Harry for a beat too long, swallowed hard, and then silently waved his hand at a chair off to the side of his desk. Harry slid closer, up to the edge of the desk, and dropped his bag on the floor.

"Hello, professor," he said. Professor Black nodded, not looking at him.

"Hello, Mr Potter. Please take a seat."

For a second, Harry considered refusing and perhaps sliding onto the man's lap instead, but this close he could see that Professor Black's neck had gone red, and that his cheeks had darkened more than his usual tan.

He sat down. Professor Black had him help mark the first-years' classwork, and the first ten minutes were spent in absolute silence as Harry tried in vain to focus. He felt hyper-aware of his professor, of the heat that radiated from his body. Harry had always been someone who easily felt cold, and Professor Black felt almost like a furnace. He wondered what it might be like to curl up to him, press himself between his professor's arms and torso on cold nights. 

How was he getting this sentimental already?

Eventually, he managed to get his mind off the musky smell of the alpha, his slow breathing, the way his hands moved across the page as he read, and onto the task before him. It wasn't long before he was trying and failing to suppress his laughter at the work he was reading. Some of the answers these kids had written were so absolutely _ridiculous_ —had _he_ been this stupid at age eleven?

Professor Black looked over. He was smiling, like he knew exactly what Harry found so amusing, and Harry couldn't help but show him. "What are the effects of the spell _Stupefy_?" He chuckled. "Apparently, it amazes you. _That's_ the answer. I just—"

Professor Black was grinning now. "Oh, god, but that's not the dumbest thing I've seen today either," he confided. "Earlier today, I was teaching the third years about Cornish pixies and their effects on the forests they live in, and a Ravenclaw student—who shall remain unnamed!—actually asked me if it was true they ate humans."

And then he just kept talking. Harry watched in amazement as Professor Black's tense shoulders relaxed, his stiff smile easing into untroubled laughter. He told Harry about how he'd once ridden a Hippogriff, and how it had attacked his schoolyard rival. He told him about swimming with mermaids and outflying a Dragon and slaying a giant serpent, though he seemed a little short on details about that last one, and Harry might have been inclined to call him on his bullshit.

Except, despite how unreal these stories seemed, Professor Black seemed so earnest and _honest_ that Harry thought he'd believe anything his professor told him. He couldn't help but smile at Professor Black, and his professor smiled back at him almost tenderly before he seemed to realise himself, and blinked.

Perhaps he thought he'd said too much. Harry bit his lip as he watched Professor Black's open expression shutter, and tried to distract him. "You look a lot like me," he blurted, and then wanted to slap himself, because really? Though there were similarities in their features, they still looked like different people; nobody could ever mistake one for the other. Any resemblance must just have been accidental—passing. But the thought wouldn't leave him, stuck in his head like a persistent cough. And even as Harry waited expectantly to be called out for his ridiculousness, Professor Black didn't laugh, or look at him like he'd said something stupid. Instead, he stiffened, like Harry had asked him something much too personal.

Harry swallowed. "I mean, you look like you could be my father. Are you sure you're not—that is, I know the Blacks and Potters are related, but—"

Professor Black remained silent. Harry waited, but when he still didn't reply, Harry got up and slid himself onto the desk, right in front of his professor so that the man was between his legs. He leaned back onto his palms, chest out, and cocked his head to the side. Professor Black was going red again, and his eyes kept drifting up to the space between Harry's legs, and the arch of his chest where his nipples might show if he hadn't been wearing a shirt. 

He tried to keep his gaze away, but he failed so miserably that Harry couldn't help but smile at the attempt. It was cute, even if it was useless.

"You look like you could be my father," he said again. "Maybe I should call you _Daddy_?"

And Professor Black groaned. It was loud, and clearly unintended, but it was the sound of defeat as well as arousal. Harry couldn't help but feel smug. Professor Black dropped his head to Harry's thigh, his forehead pressing warmly against his hip, and he moaned again. "You're going to be the death of me, darling," he said.

Harry felt almost too stunned to continue—the change was so sudden, that despite all of his efforts, Harry had still expected hesitation on Professor Black's part. To realise that his professor must want him just as much as Harry wanted him was gratifying, and more than a little flattering. He let his hand drop to Professor Black's hair—it was usually slicked back as best as possible in an attempt to seem neat, but by the end of the long day it had begun to curl loosely on top of his head again. Harry was reminded strongly of his father's hair, of his own hair before he'd grown it out.

Professor Black pressed a kiss to his upper thigh, soft as you please, and Harry flushed. He wanted so badly to strip for this man, to let him fuck Harry—and it wasn't a new desire, but the strength of it certainly was. Because, despite all the boys Harry had been with, and all the boys he'd loved, he'd never once let any of them put their cock in him.

He'd let _Professor Black_ stick his cock in him.

"Daddy," he whispered again. His voice had gone strangely high, but Harry didn't really have the chance to feel embarrassed about it, because Professor Black was making a sound that could really only be described as a _growl_. It stunned Harry into stillness, and Professor Black used the opportunity to drag Harry forward and onto his lap. His hand, large and calloused, slid up the back of Harry's neck and into his hair, sliding through the loose strands of his half-up braid. He seemed fascinated by it—pulling Harry closer, Professor Black pressed his face into his neck, and rolled his hips up against Harry's arse.

He felt _huge_. Logically, Harry knew he was probably biased, and that his arousal was probably playing a significant part in how well-endowed his professor seemed, but—

But Professor Black felt like he was _hung_.

"I want—" and he gasped as Professor Black thrust up again. "Please!" He whined. "Daddy please, want you in my mouth, want you in my _pussy_ —"

Professor Black's hand tightened in his hair, and he pulled it back hard. "You look so innocent," he groaned. "Everyone thinks you're _such_ a good boy." His voice had gone deeper, huskier, and Harry could feel it reverberate in his bones. He tried to lean forward into Professor Black's mouth, but his head was pulled too far back.

And then Professor Black's other hand was on his chest, and he was pressing Harry back to lie on the table. He kept Harry there, pushing himself close between his legs, his bulk spreading Harry's thighs wide. Harry smiled up at him coyly, pleased at the sight his Professor made—flushed, his eyes nearly black with lust, his mouth wet. Harry wondered how much further he could push this.

He reached up to his collar, and started to unbutton his shirt. Professor Black let him, watched him undo his tie and half of his shirt with attentive eyes, and when the fabric had parted enough that Harry's nipples could be seen, he tore the rest apart. Harry's shirt buttons went bouncing, but Harry couldn't pay attention over the sound of his professor's breathing, and the thundering of his own heart.

And then Professor Black bent down, and licked Harry's nipple. "You're so cute here," he groaned, "so _pink_." His voice had gone gravelly, and the sound went straight to Harry's cock.

Harry gasped in pleasure, pushing his chest up into his professor's mouth. Professor Black pinched the other one in reprimand, his touch harsh enough to make Harry whine. Harry knew he'd feel this for days yet. Every touch of Professor Black's on his chest made them feel more sore, more _sensitive_ , until he felt even the negligible air currents in the classroom keenly. Meanwhile, his professor had moved down to Harry's trousers, and by the time his mouth let go of his nipple, Harry was naked from the waist down.

Professor Black's eyes went wide, and for a brief second Harry felt self-conscious. Had professor Black ever been with an omega before? Perhaps he'd only been with beta and alpha males, and expected something similar in terms of size from him? He waited, biting his lip, and had almost decided to get up when Professor Black's smile stretched into a wicked smile.

"Cute," he commented. Harry could feel himself flushing, but he didn't know if it was from embarrassment or pleasure, or perhaps a mixture of them both. As he watched, Professor Black dipped his head, and laid a kiss right on the tip.

"I knew omegas were tiny," he continued, licking the shaft. "I just didn't know _how_ tiny." Harry moaned, grabbed Professor Black's hair to urge him on, but—

Professor Black's fingers went down further, past his cock, and then he was touching—

They both froze. Harry felt unbearably aroused, but more than that, Professor Black's touch felt like a revelation. The knowledge of what his fingers were touching was just as intoxicating as the feeling itself. Professor Black's fingers had gone completely still, like he was confused, but as Harry watched his fingers started to move. He curled them against the mound of Harry's smooth sex, the tips dipping between the folds to where he was soaking wet.

Harry couldn't help but moan, still holding on to Professor Black's hair and broad, steady shoulders. Professor Black's breath was hot against Harry's cock. Harry felt so overwhelmed he felt like he could explode with it.

"When you said pussy…" Professor Black murmured. He seemed amazed, like Harry was a miracle or something. The feeling of being regarded like that, like he'd _impressed_ Professor Black in some way, just made him ache more. He spread his legs wider, eager, and mewled when Professor Black suddenly slipped a finger inside.

He didn't give Harry time to adjust. Of course, Harry had fucked himself with his fingers before, and had even let Cedric Diggory eat him out one memorable time in the back of Greenhouse 3. But Cedric had been so gentle with him, so hesitant—it had been a first time for the both of them, and it had showed in the tentative movements of his tongue. Professor Black was obviously surprised, but even so he moved and fingered Harry with a confidence that came from practice, and from knowing oneself intimately.

Harry wondered if he had a kink for older men.

He felt the faintest flicker of shame at the way Professor Black's eyes were intent on what was between his legs—like a reminder that this was obscene, immodest, _wanton_. Professor Black's face was so close to his pussy, right down between Harry's legs, and Harry felt—

Harry felt more attractive than he ever had. It pushed him to behave in ways be might not have otherwise. Harry wasn't really known for being shy, what with the sheer number of dalliances he'd had, but they were usually teenage fumblings and late-night rendezvous, committed under the cover of night and clothing like it was a sin. There was none of that here, with Professor Black so hesitant and still so shameless. And when he curled his fingers inside Harry just _so_ , he couldn't help but close his legs tight around the broad hand and Professor Black's head. His face was pressed just above Harry's knees, and though he'd stilled at Harry's reaction, he moved his head now to press a kiss to the skin there. It made his rough chin scrape across Harry's thigh, leaving bright pink marks that faded within seconds.

But it was the sensation of it—a feeling that should be painful, but wasn't. Harry whined, humping up against Professor Black's hand helplessly. His professor removed his fingers, and just when Harry opened his mouth to complain, pressed his face down between Harry's legs.

His mouth was much softer than his fingers, wetter and smoother than his hand. He licked into Harry's pussy like a man starving, fucking his tongue into Harry's hole and sucked on the soft skin there. Harry screamed, pulled almost viciously at Professor Black's hair, but the man didn't seem to notice. He pushed a finger into Harry again alongside his tongue, and fucked Harry with until he felt like crying. Harry's thighs were wet with his arousal, his pussy soaked, and everytime he thrust down onto Professor Black's face, his stubble would scratch the softness of Harry's inner thighs. It burned, but pleasantly—like tingles of static strengthened until they were on the edge of hurting, but still good. 

He'd have the marks tomorrow, Harry knew. He was glad of it.

When he came, he felt like the world went white. His mouth was open but soundless, and still Professor Black fucked him through it until it nearly hurt. He could feel the tremors pass through his body after, the way his pussy twitched with the after effects of his orgasm.

Harry pulled Professor Black up from between his legs and sat up. Keeping his fingers curled in the man's hair, he kissed him, and tasted his own orgasm on his professor's tongue. Professor Black's face was wet, but Harry didn't mind—he kissed so well, Harry felt like he could be satisfied just making out with Professor Black.

After, he curled close, sitting pretty on the man's lap, and felt Professor Black stiffen by the second.

"What is it?" he murmured, lazy with the sex and afterglow. Professor Black said nothing, but the way his hands tightened on Harry's hips made him move away so he could look at his professor's face.

Professor Black looked back down, equally silent, and then—

"We shouldn't have done this." His voice was soft, almost affectionate, but it made Harry feel cold all the same.

"I don't understand," Harry said eventually. "Because you're a teacher and I'm your student? I know we're not supposed to, but I'm an _adult_ —”

"That's not why," Professor Black interrupted. "I mean it is, it _should_ be, but—"

He broke off. Harry waited for him to finish, and when he didn't, curled his fingers tight about Professor Black's biceps. "Why do you look like me?" he asked quietly.

And Professor Black—harder, older, _Alpha_ , with eyes the colour of his mother's and mouth in the shape of his own, said, "Because I _am_ you."

* * *

Harry was _done_. He'd been watching Professor sigh and sulk for the better part of a week, looking so miserable it made his chest feel uncomfortably tight. He was acting like Harry had broken up with him or something, like he'd broken Professor Black's _heart_. He was making Harry feel guilty, his gaze so sad and dull every time they locked eyes, and Harry tried to make it better, he really did! But every time Harry approached him, he was soundly ignored, his professor coming up with a million excuses to avoid him. It had gotten to the point that Harry noticed pitying gazes from his friends every time it happened, and well. That was _that_.

Admittedly, Professor Black's identity had come as a shock. Harry had expected him to admit to being a cousin or an uncle, or even—as unreasonable as it sounded, for Professor Black to tell him all about some sordid affair he'd had with his mother.

To find out Professor Black was _him_ —a Harry Potter from another world, felt absolutely ridiculous. A part of Harry still couldn't believe it—after all, they were so _different_. For one, Harry was an omega, and his professor clearly an alpha. But even despite that, they behaved so differently—Professor Black came across as almost antisocial. He was friendly and helpful, but distant. Harry thought he seemed rather lonely, but there was an anger—an _aggression_ —in him that was was being the normal for alphas, and completely unlike Harry himself.

And yet, when he'd told Harry the story of how he'd gotten to be in this world, he'd seemed so earnest and transparent—much in the same way he had when he'd told Harry about all his amazing adventures. By all rights, Harry should report him as having a few screws loose and stay away, but…

But Harry believed him.

Of course, if he believed Professor Black, then he also had to accept that he'd let himself eat out his own pussy, and it made sense then that Professor Black felt so bad about it. Harry thought, lazily, that he should maybe feel disgusted—was this like incest? Or was it more like masturbation?

He should feel disgusted. But he didn't. He only wanted Professor Black all the more, wanted his hopeful, sad eyes and strong hands and broad shoulders. And if Professor Black wouldn't make the first move, then Harry would have to do it himself. So, he came up with a plan.

* * *

The spell wasn't even that hard to find. It wasn't actually meant for the purpose Harry was using it for—originally, it had been used to inflict pain on others, and it was the spell where the idea of voodoo dolls had come from. Later, it had become so easily combatable that it was only really used for pranks, but Harry had a whole different idea.

That afternoon, sitting in DADA class, he tried to get comfortable. He watched Professor Black intently, eyes roaming the dark circles under his eyes, barely hidden, and the stubble that had grown enough that it could probably be called a beard now. For a second, he forgot all about his mission, lost in admiring how handsome Professor Black looked. But the toy inside him was large and hard, and pressed against his pussy so deliciously that it was hard to ignore.

He waited until Professor Black had sat down, feeling gracious, and then cast the spell under his breath. Just as he did, he wriggled his arse, spreading his legs a little to get himself used to the the dildo inside his pussy, and watched his professor carefully.

And Professor Black did not disappoint. Immediately, his head shot up. He eyed the entire class with narrowed, suspicious eyes, and then his eyes came to land in Harry, and Harry didn't look away. He spread his legs wider and rolled his hips, slowly, clenching around the toy, and watched as Professor Black's hand dropped down between his own legs.

He'd be feeling Harry on his dick. The thought made Harry flush warmer, made him want to fuck himself on the dildo harder. He barely remembered that he was, in fact, in class, and could not just shove his hand down his own trousers. Instead he made do with watching the flush rise on Professor Black's face, and bouncing down onto the toy as much as he could without arousing suspicion.

It didn't take long before Hermione noticed. "Harry," she hissed, "sit _still_!”

Her head was bent low over her parchment, and Harry knew she wouldn't look up, so he didn't look away from Professor Black as he replied, loud enough for him to hear too, "I'm just all keyed up, Hermione."

Hermione tsked at him. "It's all that sugar you had for lunch. I told you to stop with the treacle tarts, didn't I?"

Harry shifted his hips again, grinding down on the toy inside him. "But Hermione," he said breathily. "I just lo— _ah_ , love it."

Professor Black's eyes went all dark at the sound of Harry's moaning. Hermione didn't really care enough to reply, used to Harry's antics, but Professor Black seemed to be of a different opinion.

"In that case, Mr Potter, please step outside."

Harry couldn't help but smirk at the barely controlled lust in his professor's voice. He stood up and fluttered his eyelashes at Professor Black. "Yes, _sir_ ," he purred, and then he was sauntering out of the door and pressing himself against the cool brick walls of the hallway.

He only gave Professor Black a few seconds' reprieve. But out here, there was no class full of students to keep him in check, and no people wandering out in the corridors to convince him to keep his hands under control. So before two minutes had passed, Harry found himself on the stone floor, legs apart, fucking himself on the dildo inside himself as hard as he could without actually touching himself or taking his trousers off. He managed to thrust down only thrice—by the fourth, he heard Professor Black's strangled voice shouting at him to come back inside.

He sounded so frustrated and so near to losing his control that it made Harry burn with excitement. He got up on shaky legs, trying not to let go of his own control and just run to the bathroom to finish himself off, and entered the classroom with confidence. As he walked, he made sure to keep his eyes on Professor Black's, and swayed his hips in a way he knew was attractive.

Professor Black had already gone red, but now his face seemed to darken with both lust _and_ anger. He looked like he wanted to get his hands on Harry and _wreck_ him, and Harry very much wanted to let him.

He didn't know how they managed until the end of the lesson. Harry couldn't stop shimmying onto his dildo, too aroused and high-strung to settle down. Similarly, Professor Black's face had gone all scrunched up, like he was in pain or like he urgently needed to take a break. But he taught the rest of his lesson through gritted teeth, determinedly not looking at Harry, and Harry decided it was in his best interest not to antagonise Professor Black any further.

He didn't need to be told to stay behind. Professor Black dismissed the class, and Harry took his sweet time packing up. He told Ron and Hermione to leave without him. Ron tried to insist on waiting anyhow, but Hermione had caught on, and simply rolled her eyes before she dragged him out after her. Harry thanked her mentally, and promised to buy her that book he knew she'd been hunting the Hogwarts library for lately.

And then, him. Professor Black seemed aloof, but as soon as the door shut behind the last pair of students he was out of his chair and across the room in the blink of an eye. He sent a wordless spell at the door as he did, locking it and putting up a silencing ward in quick succession. Harry only distantly registered this over the ravenous look on his professor's face, but the knowledge that Professor Black planned do something to him that required a silencing ward only made him more excited.

He rolled his hips over the dildo, his lips parting despite himself in an embarrassingly desperate whine, but before he could do more Professor Black was on him. His mouth was hungry over Harry's, his teeth worrying over Harry's bottom lip until it felt swollen and unbearably sensitive. It almost _hurt_ , Professor Black's stubble rubbing against his mouth and his cheeks as he pressed their mouths together furiously. Harry whined into Professor Black's mouth. His fingers clenched in the man's shirt, and he used his hold to press himself closer to Professor Black, up and out of his own chair.

His professor's large, warm hands came down on his arse to hold him up, and then Harry had his legs wrapped around Professor Black's waist, and he could feel the man's hard, large cock between his own legs. He moaned into Professor Black's mouth, loud and shameless, and rolled his hips against Professor Black's.

And then Professor Black was slamming him down onto his desk, and Harry couldn't help but gasp and let his professor move him as he pleased. His pussy felt so hot and wet and uncomfortable that he reached down to strip himself, but Professor Black's firm grip stopped him. He pushed Harry down into his back, and then stripped his trousers off himself. Harry's panties were practically soaked underneath—he could feel the soft, plain cotton as it stuck to him, and he couldn't help but arch in an effort to get his professor to remove those too.

But it was like Professor Black was entranced. He pressed his fingers against the wetness, pushing the crotch of Harry's panties up against his pussy and against the hole there. Harry gasped, unsure of how he felt about it—the fabric, pressing nearly inside him, felt so odd, and Harry didn't know if it was uncomfortable or pleasurable yet.

All he knew was that he wanted Professor Black, and that Professor Black was playing with him.

On a sudden burst of inspiration, Harry swung one leg up and over Professor Black's shoulder. He curled the other tighter about his professor's waist, and then bucked up into the man's broad, large hand. His pussy was much more open like this, and when he pushed, Professor Black's fingers pushed not against skin, but against something much harder.

"Oh, you're a right little slut, aren't you," he murmured. His voice was quiet, calm, but his words were so suddenly profane that it made Harry whine. He didn't know quite how to react, but it didn't really matter, because Professor Black was pushing the crotch of his panties aside and taking hold of the dildo inside him.

He moaned, loudly. Professor Black didn't react, slowly pulling the toy from Harry, making him feel every inch he'd shoved up there. It was a long one—Harry had hoped Professor Black would be the one to pull it out, and he'd wanted—just a little bit—to impress. And Professor Black certainly _did_ seem impressed, his mouth going wet and tight as he watched the toy slip out.

When he'd pulled about half of it from Harry's body, he paused. Harry realised he was panting, and took a second to calm himself before he tried to speak.

"Daddy—” he started, his voice embarrassingly high, but then Professor Black's eyes went wide, and he twisted the dildo into Harry's pussy again. Harry mewled, rocking up into Professor Black's touch, but Professor Black was pulling the toy out again, and watching the way Harry's slick dripped from its length.

And Harry was so wet, he didn't think his cunt had ever been this soaked before in his life. Everything felt hot and slippery and messy, but Harry had also never wanted someone to make a mess out him more than he did then. His naked, empty pussy twitched, and he reached up to slide his fingers across Professor Black's beautifully sculpted chest.

"Please, Daddy," he whispered huskily. "Won't you fuck me?"

Professor Black looked at Harry, and brought the tip of his wet, used toy to his mouth. He licked at the slick there slowly, like he was savouring it.

"Delicious," he said, and then reached down to undo his own trousers.

His cock was just as huge as Harry remembered. It was fully erect, and when Professor Black pressed it against his thigh, he felt how warm it was too. Harry wondered if he should feel afraid of it—after all, this was the first time he'd be letting someone fuck his cunt, but instead of apprehensive he just felt excited.

It was daunting, but Harry trusted Professor Black more than he perhaps should.

Professor Black went slowly. Harry was loose, open and wet and very much ready, but even so Professor Black held him like he was glass. He fucked the tip of his cock into Harry in small, rounded thrusts, and then pushed in a little more, and a little more, filling him up slowly and steadily. Harry's pussy felt unbearably sensitive. Despite the fact that he'd had toys this size before, he felt like he was being stretched almost beyond him limit. But it felt amazing, like an achievement he hadn't even realised he'd set for himself had been attained. And looking up at Professor Black, seeing the way his eyebrows pinched in and his teeth clenched in barely restrained pleasure, hearing the way he groaned when he bent down into Harry's neck, was a gift all of its own.

Professor Black curled his fingers tightly around Harry wrist and hip, tight enough that it'd leave bruises, and Harry counted it as a win.

The rest of their time seemed to pass oddly, a hazy blur of intense pleasure and sudden, stark details. Harry wasn't sure what filth came from his mouth, didn't remember what kind of things he begged his professor for. All he knew was that he felt both incredibly full and always yearning, and that Professor Black's mouth tasted like black coffee. Eventually even the slight discomfort of being stretched disappeared, and all Harry wanted was more. Every thrust of Professor Black's cock into his pussy was strong and loud, the wet slaps obscene and shameless. They were lewd, and they made Harry fuck his hips up onto Professor Black's cock even harder.

He didn't realise what it was at first. Professor Black's cock seemed to grow inside him, and at first Harry wondered if he was only imagining it. But soon enough the feeling became impossible to explain away—he was been stretched incredibly wide, almost more than he could handle. He gasped, his eyes wide and wet with overwhelmed tears. Professor Black's mouth twisted oddly, like he wanted to stop but couldn't. His eyes were rapt on Harry's tears and in Harry's bitten-red mouth, and his hips stuttered in his movement—he was worried for Harry, but liked the sight of Harry's tears despite himself.

  
  


But Harry didn't want him to stop, even though it felt terrifyingly large and intense—it was a sense of pride, and it was a carnal hunger in him that was only now being fulfilled. He understood, now, exactly _what_ was inside him. And though he'd never taken a knot before, he wanted more than anything to take Professor Black's right now.

"Harder, Daddy," he moaned. He didn't want Professor Black to hesitate in the least, wanted him to fuck his knot into Harry so hard it'd lock them together for hours, wanted to feel the stretch and ache in his pussy every time Professor Black so much as shifted. And Professor Black needed no further convincing. He thrust into Harry hard once, and again, his knot growing with every push into his hole. Harry could barely breathe with it, and almost felt dizzy with the feeling of being so incredibly _full_. Professor Black's knot grew larger than he'd ever imagined it would, and for a second Harry thought it wouldn't make it inside him on the last thrust. But then Professor Black's hands wrapped tight around his hips, and he shoved his cock into Harry's pussy like a man possessed, and Harry whined as he felt his large, solid knot push into his body.

Afterwards, Harry listened to Professor Black's breathing as it slowed, and let himself relax around the knot in his cunt. He felt hot inside, and imagined that it was Professor Black's come, filling him up so much he'd leak the moment they parted. He couldn't be sure, of course—everything felt wet and sore and sensitive, and Harry couldn't separate which feeling came from what. But he let himself think about Professor Black fucking him again, thought about him joing Harry for his heat, and what it might be like to let the man breed him.

He didn't think he wanted a child, but somehow the idea of being heavy with Professor Black's made him want to go at it all over again.

Eventually, his professor had calmed quite significantly. His knot was still hard and large inside Harry, locking them together, and for a second Harry let himself feel smug about it—Professor Black couldn't run from him this time. He'd have to look at Harry and know what they'd done, and there'd be no frenzy of lust to pretend he didn't realise what he'd done.

But it seemed Professor Black didn't really want to go the denial route again. He looked at Harry with an unbearably soft look in his eye, so tenderly that for once, Harry felt stupefied. How could he say anything in the face of such affection? He'd anticipated a lot of reactions, from shyness to anger, but never had he considered that Professor Black would look at him like—

Like Harry was the most precious thing he owned.

He felt himself blushing at the sight, and wondered if his own expression was just as hopelessly fond.

There were foreign words on his tongue, a warmth in his chest that threatened to spill over, but it felt too new, too vulnerable to let out into the world. Harry couldn't let himself, not right now. Instead, he cleared his throat, and wrapped his arms around Professor Black's neck.

"What now, Professor?"

Professor Black smiled. "Firstly, I think you've earned the right to call me by my first name."

There was a pause, and then, "Harrison." A name so like his own, but nevertheless one that belonged, in his mind, only to the man above him. He said it again, "Harrison," and then laughed.

"I'm going to call you that from now on," he promised.

Harrison frowned, confused. "I know, isn't that kind of the point?"

"Exactly," Harry grinned. His legs had loosened from around Harrison's waist, but now he wrapped them close again, grinding Harrison's cock deeper inside his pussy and clenching around it. "I hope you won't regret this later, _Professor Harrison_."

After all, Harry was not the sort to feel shy. Once given permission, he'd be sure to call Harrison by his first name _all_ the time—even in class. He could see the realisation dawning in Harrison's eyes, but before he could say anything about it, Harry raised his finger and tapped Harrison on the nose.

" _Ah ah ah_ , no take-backs."

Harrison groaned, theatrically loud. What _have_ I gotten myself into," he murmured, and bent to kiss Harry on the neck.


End file.
